WO1994021879A1

WO1994021879A1 - A window stay

Info

Publication number: WO1994021879A1
Application number: PCT/NZ1994/000023
Authority: WO
Inventors: Ronald Percival Davis
Original assignee: Ronald Percival Davis
Priority date: 1993-03-19
Filing date: 1994-03-21
Publication date: 1994-09-29
Also published as: GB2276915B; GB2276915A; NZ270334A; NZ247210A; GB9405529D0; AU6387194A; EP0690949A1; EP0690949A4

Abstract

A four bar friction window stay for mounting a window sash in a window frame has a geared pivotal connection between the frame end of the short arm (1) and the frame plate (5), comprising a gear (9) fixedly mounted to the frame end of the short arm (1) which engages a rack (10) on the frame plate (5) such that during closing and opening of the stay the frame end of the short arm (1) is moved towards and away from the head of the stay. The window stay may also incorporate a locking head (13, 14) for security, a movable long arm frame plate joint which allows the window to be opened widely for emergency egress for example, and a safety catch which can be used to limit the angle of opening of the window.

Description

A WINDOW STAY

FIELD OF INVENTION My present invention comprises a friction stay for a window.

BACKGROUND The four bar friction window stay (see New Zealand patent No. 144922/146130/146886) has been sold in many countries in its basic and subsequently refined forms.

With conventional four bar friction stays, even when the window sash is closed, the stay itself is still several degrees open. This is necessary to ensure correct operation of the stay when the window is again opened. With the four bar geometry, designers have ensured that the stay is slightly open even when the window is closed because of the danger that otherwise the stay might not operate correctly and that the head of the window could begin to move outwardly before the bottom of the window sash, which would result in jamming of the stay.

Windows produced from uPVC instead of aluminium or wood have become popular, particularly in the replacement window market. The uPVC material is produced by extrusion and is then cut and the window sash(es) and frame(s) are constructed. A common standard uPVC extrusion profile has a cavity comprising a narrow groove to accommodate the stay between the sash and frame to suit pantograph type stays, and which will not accommodate a conventional four bar friction stay.

Also, because the four bar friction stay has not been allowed to close fully, for various reasons this has inhibited the use of some form of integral head locking mechanism with the four bar stay. Some form of head locking mechanism is desirable because of another disadvantage of the four bar stay, which is that the head can be forced open from outside the window frame, by levering between the peripheral sealing flange at the head of the window and the window frame with a crowbar for example. A separate locking device can be added between the window sash and frame on the inside of the window to counter this danger, but this is not as desirable as if an integral mechanism could be used. For as long as the four bar friction stay has been produced, these problems have remained.

SUMMARY OF INVENTION My present invention provides an improved or at least alternative form of friction window stay which possesses advantages over the conventional four bar stay as will be described.

In broad terms the invention comprises a four bar friction window stay for mounting a window sash in a window frame, comprising a long arm and a pivot joint between the frame end of the long arm and a frame mounting member (as herein defined) for securing to the frame rf a window and a pivot joint between the sash end of the long a and a sash mounting member (as herein defined) for securing to the sash of the window, a short arm and a pivot joint between the sash end of the short arm and the sash mounting member at a point spaced from the short arm-sash mounting member pivot joint and a geared pivotal connection between the frame end of the short arm and the frame mounting member at a point spaced from the long arm-frame mounting member pivot joint comprising a gear fixedly mounted to the frame end of the short arm engaging a rack on the frame mounting member such that during closing and opening of the stay the frame end of the short arm is moved towards and away from the head of the stay.

Preferably the arrangement is such that when the window stay is fully closed the short arm and the long arm are aligned with the frame mounting member.

The long arm-frame mounting member pivot joint of the stay may be a fixed pivot joint or it may be a sliding or travelling pivot joint as will be described, in which case a third arm pivotally connected to the frame mounting member nearer to the long arm-frame mounting member pivot joint than to the short arm-frame mounting member geared pivot joint, and to the sash mounting member nearer to the sash mounting member-long arm pivot joint than to the sash mounting member-short arm joint, is preferably provided. Preferably the stay of the invention incorporates integral means to lock the head of the stay against forced opening, comprising frame engaging means such as a protrusion on the upper end of the sash mounting member which engages sash engaging means such as a recess on the frame mounting member as the stay is closed.

The stay of my invention is suitable for use with both top hung and side hung window sashes. With preferred forms of the stay of the invention when the window is closed the stay is also fully closed i.e. the sash mounting member and long arm are fully aligned. This allows the stay to be used with common standard uPVC window profiles with standard cavity sizes. Also, in initial opening the head of the stay has a downward and then an outward movement. This enables the stay to employ an integral head locking mechanism.

DESCRIPTION OF DRAWINGS Preferred forms of friction stays of the invention are illustrated, by way of example and without intending to be limiting, in the accompanying drawings, wherein:

Fig. 1 is a view of a preferred form window stay of the invention from one side in its fully extended or open position.

Fig. 2 is a view of the stay of Fig. 1 in its closed position. Fig. 3 is an end view of the preferred form stay of Figs 1 and 2 in the direction of arrow A in Fig. 2,

Fig. 4 is a close-up view of the short arm-frame plate joint of the stay of Figs 1 to 3 with parts cut away to show the gear and rack mechanism of the stay.

Fig. 5 is a cross-sectional view along line I-I of Fig. 4,

Fig. 6 is a cross-sectional view of a preferred type of friction pivot joint between the sash plate and arms of the stay suitable for use when the sash plate is formed from a plastics material, also showing a mounting screw as would be used in practice for mounting the stay to a window sash.

Fig. 7 is a view from above of the joint of Fig. 6 (with no mounting screw shown) ,

Fig. 8 is a cross-sectional view through the end of the sash plate of Fig. 6 without the arm, fixing means, and mounting screw of Fig. 6,

Fig. 9 is a view from above of the end of the sash plate shown in Fig. 8, in the direction of arrow B in Fig. 8, Fig. 10 is a cross-sectional view through a preferred form cap screw fixing means for use in the joint of Figs 6 to 9 (and also Figs 17 and 18),

Fig. 11 is a view from above of the preferred form cap screw fixing means in the direction of arrow C in Fig. 10,

Fig. 12 is a view of a preferred form movable pivot joint which may optionally be used between the long arm and frame plate of window stays of the invention.

Fig. 13 is a cross-sectional view of the preferred form movable pivot joint of Fig. 11 along line I-I in Fig. 12,

Fig. 14 is a cross-sectional view of the preferred form movable pivot joint along line II-II in Fig. 12,

Figs 15 and 16 schematically show the operation of the movable pivot joint of Figs 12 to 14 to enable a window to be opened beyond its normally fully opened position in an emergency.

Fig. 17A is a cross-sectional view of a form of friction pivot joint alternative to that of Figs. 6 to 9 between the arms and the metal sash plate when the sash plate is formed of metal. Figs 17B and 17C showing steps in assembly of the joint. Figs 18A, 18B and 18C are views from above for each of Figs 17A, B and C,

Fig. 19 is a view of a stay of the invention with a safety catch which may optionally be used, from one side, shown with the safety catch engaged and the stay opened as much as is possible when the safety catch is engaged in hard outline, and showing in phantom outline the position of the safety catch when not engaged.

Fig. 20 is an end view of Fig. 19 in the direction of arrow D thereof.

Fig. 21 is a view of a part of the stay showing the safety catch from the other side to that of Fig. 19, showing the safety catch engaged, and

Fig. 22 is a side view of another preferred form of stay of the invention from one side and open.

DESCRIPTION OF PREFERRED EMBODIMENT STAY WITH GEAR-RACK MECHANISM

Referring to Figs 1 to 3 the preferred form stay illustrated in these drawings comprises a short arm 1 and a long arm 2. The arms are preferably formed from stainless steel or could alternatively be formed of aluminium, for example. The frame end of the long arm 2 is pivotally connected to a frame mounting member comprising a frame plate 3 for securing to the frame of a window, by way of suitable friction pivot joint 5. Optionally a movable pivot joint between the lower arm and frame plate may be employed, as will be described. The frame plate 3 is suitably formed from metal such as stainless steel.

The sash ends of the short arm 1 and long arm 2 are pivotally connected to a sash mounting member comprising a sash plate 6 for securing to the sash of the window, by way of a pivot joints 7 and 8 which are preferably also friction pivot joints. In the preferred form stay shown in Figs 1 to 3 the sash plate 6 is formed by injection moulding from a plastics material such as acetyl or other self lubricating and wear resistant synthetic material, but the sash plate could alternatively be formed of metal such as stainless steel or aluminium.

The frame end of the short arm 1 is connected to the frame plate through a gear and rack pivotal connection particularly shown in Figs 4 and 5. A toothed gear 9 is fixed to the frame end of the short arm 1. While the gear 9 may have teeth all the way around its periphery, teeth only part way around its periphery are required. A rack 10 is formed on the frame plate 1 as shown. In the preferred form the frame plate 5 is channel shaped in cross-section, as best seen in Fig. 5. The rack 10 is formed on one side of the channel shaped interior of the frame plate so that the gear 9 on the end of the short arm 1 will engage the rack 10 on the frame plate as shown in the drawings.

During opening and closing of the stay the short arm 1 will pivot around its frame end as indicated by arrow E in Fig.

4. As it does so it will rotate the gear 9 which will move up and down on the rack 10, in turn effectively shifting the point at which the frame end of the short arm 1 is connected to the frame plate 5 up and down along the frame plate by a small amount as indicated by arrow F. When the stay is pulled open as shown in Fig. 4, the end of the short arm 1 will be at the bottom of the rack 10 i.e. closest to the long arm-frame plate pivot joint. When the stay is fully closed, the frame end of the short arm 1 will be at the other end of the rack 10, closest to the head of the stay. As the stay is opened and closed, the gear 9 will move down and up the rack 10, moving the point of pivotal connection of the short arm 1 to the frame plate 5 as it does so.

To protect the gear-rack mechanism of the short arm- frame plate joint from dirt, a plastic cover 11 may be provided over the gear-rack mechanism. In the preferred form the plastic cover 11 is slidably mounted by grooves 11a in its sides which engage extending edges 5a of the frame plate 5 as shown in Fig.

5. The gear 9 has a shaft by which it is fixed to the end of the short arm 1, which passes through a close fitting hole in the cover 11 so that the cover 11 moves in the direction of arrow F also, with the end of the upper arm 1 during opening and closing of the stay, along the frame plate. The cover 11 is preferably but optionally provided with screws 12 at one or both ends as shown which may also be formed of plastic material. By tightening these screws increased friction during opening and closing of the stay may be applied.

The pivotal connection of the short arm to the frame plate through a gear and rack according to the invention enables the stay to be fully closed so that the long arm 2 and sash plate 6 are aligned when the stay is in its closed position, in comparison to conventional four bar stays where, even when the window sash and stay are in their closed positions, the geometry of the stay is not fully closed i.e. the long arm and sash mounting member are not aligned as shown in Fig. 2 (with the stay of the invention) but are still a few degrees away from this position. As stated previously this reduces the overall width of the stay so that it can fit into the standard cavity of a uPVC stay window. The gear and rack mechanism also gives the stay a downward movement at the head of the stay during initial opening of the stay, and a corresponding upward movement at the end of closing of the stay, which enables the stay to work with a novel head locking mechanism as will be described.

Each of the frame and sash plates may be provided with suitable mounting holes whereby the stay may be mounted to a window frame and sash in use. In use the stay can be moved from its fully extended or open position shown n Fig. 1 wherein the sash plate and a sash mounted thereto (sash not shown) extend at an angle to the window aperture, to or towards its closed position (or vice versa) by pulling (or pushing) on handles suitably mounted to the window sash. The stay of Fig. 1 is shown in its closed position in Fig. 2, and the movement of the sash plate/short arm, sash plate/long arm pivot joints is as indicated by arrows Y and Z in Fig. 1.

HEAD LOCKING MECHANISM

Stays of the invention such as the preferred form of stay shown in Figs 1 to 5 may optionally incorporate a preferred form of head locking mechanism as will now be described. The top end of the sash plate 6 is formed with frame engaging means in the form of a protrusion 13 (see Fig. 1). A recess 14 is formed in an integral enlarged head 15 of the frame plate 5. The protrusion 13 and recess 14 each have an adjacent downwardly sloping land 13a and 14a as shown. The arrangement is such that when the window stay is closed, the sash plate 6 will move such that the protrusion 13 engages into the recess 14 as shown in Fig. 2. When the stay is fully closed and the protrusion 13 is fully engaged into the recess 14, the head of the window is locked and cannot be opened by force or prising open between the top of the window sash and the window frame. The locking mechanism can again only be opened by proper opening of the window by pushing on the bottom of the sash from within. In the form shown in the drawings the protrusion 13 is formed in the plastics material of the sash plate, and the recess 14 consists of a cut-out in the head 15 which is formed of metal at the top of the frame plate. Other forms of interlocking frame engaging means on the sash plate and sash engaging means on the frame plate are possible. For example, the respective positions of the protrusion and recess could be reversed. However, the particular arrangement shown in the drawings is most preferred. The leading face 13b of the protrusion 13 (see Fig 1) directly engages a corresponding face of the recess 14, which is preferably a metal edge, in a direct abutment. It is very difficult for the protrusion 13 to be dislodged from the recess 14 under force between the sash and window frame. Also, a screw hole 16 is provided so that a screw may fix the plastic moulding (in the case of a plastic sash plate) to the side of the sash very close to where loads would be applied during such force, to prevent breakage (see Fig. 15).

As stated previously the gear and rack mechanism of the stay of the invention gives the sash of the stay a downward movement during initial opening and a corresponding upward movement at the end of closing of the stay, which enables the stay to work with the head locking mechanism as described above to provide very strong and secure locking at the head of the window. It is preferred but not essential that stays of the invention incorporate a head locking mechanism.

PIVOT JOINT FOR PLASTIC PLATES

A preferred form of friction pivot joint is shown in Figs 6 to 9, which is very preferably employed for the pivot joints between the arms 1 and 2 and the sash plate 6 of the window stay where the sash plate is formed of a plastics material. The sash plate is indicated at 6. An arm is indicated at 1. An annular shoulder 17 surrounds and projects from the periphery of an aperture through the sash plate 6 as shown. Figs 8 and 9 show the shoulder integrally formed on the mounting plate before forming of the joint.

The arm 1 has an aperture whereby the arm is located about the shoulder 17. An annular fixing means or cap screw 18 extends through the joint and is fixed within the interior of the annular shoulder 17 and/or the aperture below, to fix the joint and apply friction creating pressure thereto so that a friction pivot joint is provided. In the preferred form the cap screw 18 is screw threaded into the interior of the shoulder 17 and aperture below. Preferably a thread is not formed in the interior wall of the shoulder 17 so that the cap screw 16 will tap its own thread and bite into the plastics material. It is possible that the cap screw could be fixed by other than screw threading, by barbs on the cap screw biting into the plastic of the interior wall of the shoulder or aperture below for example. As the cap screw 18 is inserted and screwed home the top part 17a (see Fig. 8) of the shoulder 17 is bent over to become interposed between the underside of the top of the cap screw and the arm 1 as shown in Fig. 6, so that there is no metal to metal contact. Preferably the top part 17a of the shoulder has a lesser wall thickness than the main body 17b of the shoulder as shown in Fig. 8, which shows the shoulder before placement of the arm.

In the preferred form the shoulder 17 is recessed slightly into the body of the plate 6 by annular dish recess 19 - see Figs 8 and 9. The material about the aperture through the arm 1 is pressed to a complementary shape as shown at la, so that the part la of the arm will sit within the recess 19 as a bearing surface for the arm. Alternatively the recess 19 may be avoided and the shoulder 17 may project directly from the main surface of the plate 6. The arm 1 would not then have pressed part la.

The preferred form cap screw fixing means 18 is shown in Figs 10 and 11 and comprises a flange like top portion 18a and a cylindrical body portion 16b and which is screw threaded as shown. The cap screw preferably has a hollow interior with a hex internal shape to enable screwing home of the button during forming of the joint with a hex key, and friction adjustment after installation. The joint can also be 'screwed through' with mounting screws, as well as the mounting holes. The stay is then secured to the window at the same point that loads are applied by the stay arms, particularly in casement applications.

OPTIONAL MOVABLE LOWER ARM-FRAME PLATE PIVOT JOINT

The stay of the invention may optionally incorporate a movable pivot joint as will be described for the long arm-frame plate pivot joint. This enables the window to be opened more widely than is possible during normal operation of the stay, in an emergency for example. When the window sash is fully opened, locking means of the movable pivot joint may then be released and when the window sash is pushed further the long arm-frame plate pivot joint will slide along the frame plate towards the short arm-frame plate pivot joint, allowing the sash to be opened beyond its normally fully open position. This makes escape from the window easier in an emergency for example.

A preferred form of the movable pivot joint is shown in Figs 12 to 14 of the drawings.

A slide component 32, most suitably formed of a plastic material, is captured within the interior of the channel shaped frame plate as shown in Fig. 3. The slide 32 can slide along the frame plate 1 within its channel shaped profile, in the direction of arrow G. The edge parts la of the frame plate on either side extend partly over the slide 32 so that it is captured as described. An arm 3 of a window stay, in this case the long arm, is pivotally connected to the slide 32. Preferably an annular shoulder or upstand 32a projects from the slide 32 and through a hole in the end of the arm 3 so that the arm 3 is located about the preferably plastic annular upstand. A cap screw 34 having a wide head (as in Figs 10 and 11) is screwed into the interior of the annular shoulder to hold the arm in position and apply friction to the joint. This type of joint between the arm and slide 32 is preferred but the connection may comprise any other form of pivot joint or friction pivot joint as is known in the art.

A pillar 35 projects from the bottom of the base plate as shown. The pillar 35 may be hollow so that one of the fixing screws which fixes the stay to the window frame passes through the pillar. A locking lever 36 is also pivotally mounted to the slide 32. A hole in one end of the locking lever engages over the annular shoulder of the slide below the arm 3 as shown in Fig. 12. The locking lever can pivot between the locked position shown in hard outline in Fig. 12 when a cut-out 36b in the side of the locking level engages the pillar 35 to hold the slide in its home position and the unlocked position shown in phantom outline. The locking lever has an operating button for thumb pressure at its other end 36a. When the locking lever 36 is moved to its locked position the slide 32 carrying the long arm to frame plate pivot joint can slide along the frame plate, and back again. If the movable pivot joint has been operated to open the window beyond its normally fully open position for some reason, when the window is next closed by pulling in on the sash, the movable pivot int will automatically slide back to its home position and when i sash closes it will push the locking lever back into its locke position with the locking lever engaging the pillar.

Figs. 15 and 16 schematically show operation of a four bar window stay with such a movable pivot joint as the long arm- frame plate pivot joint. In Fig. 15 the window sash WS is shown open to its normally fully open position. WF indicates the window frame. At this point the movable pivot joint indicated at MPJ may be unlocked to allow the long arm-frame plate pivot joint to slide towards the short arm-frame plate pivot joint so that the window sash can be opened further to the position shown in Fig. 16.

The slide 32 may be slidably retained by the frame plate 5 by arrangements other than as shown in the drawings. Any suitable form of pivot joint may be used. Locking means other than the locking lever and pillar may be used, the arrangement shown in the drawings being one preferred arrangement.

PIVOT JOINT FOR METAL PLATES

Fig. 17A shows in cross-section a form of joint related to that of Figs 17A to 19 that may optionally be used between an arm and a metal sash plate when the sash plate is not formed of a plastics material, or between the long arm and frame plate if a sliding pivot type joint is not used. The joint comprises a shoulder or upstand 17 formed from the metal material of the sash plate 6. The interior of the shoulder is threaded for receiving a similar threaded cap screw 16. An annular bushing is placed about the shoulder to prevent direct contact between the shoulder, the arm, and the button. Fig. 17C shows the shoulder on the sash plate before the placement of other components, and Fig. 17B the shoulder with the bushing thereon before the cap screw 16 is inserted home. The bushing has a base part 18a and an upstand part 18b which, similar to the Figs 6 to 9 joint, is bent over by the cap screw 16 when it is screwed home. Fig. 18A shows the finished joint from above without the screw for fixing the stay in place to the window sash, and Figs 18C and 18B are plan views from above corresponding to Figs 17C and 17B.

Other forms of friction pivot joints could be used, such as the joint described in my New Zealand patent specification 212599/Great Britain patent specification ???? which is incorporated herein by reference for description of this friction pivot joint.

OPTIONAL SAFETY CATCH

The stay of the invention may optionally incorporate a safety catch which limits the angle of the opening of the window stay and a window sash carried by the stay, when the safety catch is in use. A preferred form of such a safety catch is shown in Figs 19 to 21.

The sash plate 2 has an extending end 2a. In Fig. 19 the stay is shown opened to the full extent possible with the safety catch engaged. When the safety catch is not engaged the stay can be fully opened. The safety catch comprises an arm 44 pivotally coupled at one end to the extending end 2a of the sash plate 2. The other end of the arm 44 has a protrusion 45. The stay long arm 3 has a slot 46 above the long arm to frame plate bearing 47 as shown.

The arrangement is such that the protrusion 45 may entered into or removed from the slot 46 to engage or disengage the safety catch respectively. When entered into the slot 46, during subsequent opening and closing of the stay the protrusion 45 slides within the slot. The arm 44 thus linking the sash plate and long arm when the safety catch is engaged limits the possible angle of opening of the stay. When the protrusion 45 is disengaged from the slot 46 the stay may operate in its normal manner. When the safety catch is not in use the arm 44 is preferably moved to the position shown in phantom outline at 4a in Fig. 19 to be aligned out of the way with the window sash. The arm 44 is connected to the end 2a of the sash plate by a friction pivot joint so that it will remain in this position aligned with the sash when not in use and will not flop about. Optionally the protrusion 45 may have an enlarged head. An enlarged entry hole may be formed near the bottom end or midway along the slot 46. The head of the protrusion is wider than the width of the slot 46 but narrower than the diameter of the entry hole so that the safety catch may not be engaged or disengaged in anything other than one particular position. This makes it more difficult for children, for example, to disengage the safety catch since it is only possible to do this with the window in one particular position when the protrusion and entry hole are aligned.

The device is unobtrusive and not readily visible in appearance.

HEAVY DUTY STAY

Fig. 22 shows another preferred form window stay of the invention which in this case is particularly suited to heavy duty applications and particularly to carrying top hung window sashes such as large double glazed window sashes for example. The stay of Fig. 22 is generally similar to the preferred form stay of Figs 1 to 5, comprising a similar short arm 1, long arm 2, frame plate 3 and sash plate 6, with the sash plate 6 preferably being formed of a plastic material but otherwise being formed of metal. As in the stay of Figs 1 to 5, pivot joints 7 and 8 are provided between the short arm 1 and sash plate 6 and long arm 2 and sash plate 6, and also between the long arm 2 and frame plate 3, and the geared pivot joint 9/10 is provided between the short arm 1 and frame plate 3, which is similar to the geared pivot joint 9/10 of the stay of Figs 1 to 5. This stay may also incorporate a locking head 13/14 as in the stay of Figs 1 to 5 and described earlier.

However, in the heavy duty stay of Fig. 22 the pivot joint 5 between the long arm 2 and frame plate 3 is a sliding or travelling pivot joint which allows for limited movement of the joint along the frame plate 3 in the direction of arrow J as shown. The pivot joint 5 connects the end of the long arm 2 to a slide component 53 captive on the channel shaped frame plate 3 by the longitudinal edges of the frame plate engaging into grooves on the sides of the slide 53 similar to those on the side of the plastic cover 11. The slide 53 may also be formed of plastic so that a pivot joint as shown in Figs 6 to 9 may be used to connect the end of the long arm 2 to the slide. In addition, a third arm 50 is provided between the frame plate 3 and long arm 2 as shown in Fig. 22. The third arm 50 is connected to the frame plate 3 by a pivot joint 51 which may be a friction pivot joint, closer to the long arm-frame plate joint 5 than to the geared pivot joint 9/10, and to the long arm 2 by a pivot joint 52 closer to the long arm-frame plate pivot joint 5 that to the long arm-sash plate pivot joint 8 as shown.

The pivot joint 51 between the third arm 50 and frame plate 3 is fixed, while as stated the pivot joint 5 between the long arm 2 and frame plate 3 allows for some sliding movement. In Fig. 22 the stay is shown open to a large extent. In closing of the stay, the arms of the stay will move as previously described for the stay of Figs 1 to 3 except that the closing movement of the long arm 2 towards the frame plate 3 will also be accompanied by a sliding movement of the sliding long arm- frame plate pivot joint 3 away from the pivot joint 51 (downward sliding movement in the case of an awning hung sash) . Similarly, in opening movement of the stay movement of the long arm 2 away from the frame plate 3 will be accompanied by movement of the sliding long arm-frame plate pivot joint 3 towards the pivot joint 51 (upward movement in the case of an awning hung window sash) . In opening and closing of the stay the third arm 50 will pivot about the pivot joint 51 guiding sliding movement of the end of the long arm 2. Stops 54 which may for example be dimples in the frame plate 3 are provided to define the limits of movement of the slide 53/pivot joint 5 and also the geared pivot joint 9/10.

The foregoing describes the window stay of my invention and also preferred but optional forms of friction pivot joint for plastic and metal sash plates, a movable pivot joint, and a safety catch. Alterations and modifications as will be apparent to those skilled in the art are intended to be incorporated within the scope hereof as defined in the following claims. In particular, it is possible that the frame mounting member or frame plate and sash mounting member or sash plate could be integrally moulded into the side of the window frame and window sash, rather than being separate components which are attached to the side of the window frame and sar by screws or the like, whilst still employing the principle of the invention, and in this specification "frame mounting member" and "sash mounting member" are to be interpreted accordingly.

Claims

1. A four bar friction window stay for mounting a window sash in a window frame, comprising a long arm and a pivot joint between the frame end of the long arm and a frame mounting member (as herein defined) for securing to the frame of a window and a pivot joint between the sash end of the long arm and a sash mounting member (as herein defined) for securing to the sash of the window, a short arm and a pivot joint between the sash end of the short arm and the sash mounting member at a point spaced from the short arm-sash mounting member pivot joint and a geared pivotal connection between the frame end of the short arm and the frame mounting member at a point spaced from the long arm-frame mounting member pivot joint comprising a gear fixedly mounted to the frame end of the short arm engaging a rack on the frame mounting member such that during closing and opening of the stay the frame end of the short arm is moved towards and away from the head of the stay.

2. A window stay as claimed in claim 1, wherein the rack is provided along a part of one side of the frame mounting member on a wall upstanding along at least a part of one side of the frame mounting member.

3. A window stay as claimed in either one of claims 1 and 2, wherein the frame mounting member is channel shaped in transverse cross-section and the rack is provided along a part of one side wall of the channel shaped frame mounting member and the gear on the frame end of the short a.~ is captive between the rack on one side wall and the side wall on the opposite side of the channel shaped frame mounting member.

4. A window stay as claimed in any one of claims 1 to 3, wherein the long arm-frame mounting member pivot joint is a sliding or travelling pivot joint and the stay comprises a third arm pivotally connected to the frame mounting member nearer to the long arm-frame mounting member pivot joint than to the short arm-frame mounting member geared pivot joint, and to the sash mounting member nearer to the sash mounting member-long arm pivot joint than to the sash mounting member-short arm joint.

6. A window stay as claimed in claim 5, wherein the locking head comprises a protrusion on the an end of the sash mounting member providing a substantially flat contact face which is oriented to engage substantially squarely in the direction of possible forced opening of the sash against a barrier on the frame mounting member when the stay is closed.

7. A window stay as claimed in claim 6, wherein the barrier on the frame mounting member comprises a metal edge extending generally at right angles to the frame mounting member of the window stay. 8. A window stay as claimed in claim 7, wherein the protrusion providing the contact face against the barrier is formed of a plastics material or a metal which is softer than the metal of the barrier.

9. A window stay as claimed in any one of the preceding claims comprising a movable pivot joint between the long arm and the frame mounting member of the window stay, comprising a slide component retained by the frame mounting member for sliding movement of the slide component from a home position along the mounting member, a pivot connection connecting the arm of the window stay to the slide component, and manually releasable locking means normally holding the slide component in its home position.

10. A window stay as claimed in claim 9, wherein the manually releasable locking means comprises a locking lever also pivotally mounted to the slide component and means fixedly associated with the frame mounting member which is engaged by the locking lever when the pivot joint is locked in its true position and from which the locking lever may be disengaged to allow movement of the pivot joint.

11. A window stay as claimed in claim 10, wherein the means engaged by the locking lever comprises a pillar projecting from the frame mounting member adjacent the home position of the pivot joint. 12. A window stay as claimed in claim 11, wherein the locking lever includes a cut out in the locking lever open to one side of the locking lever to engage the pillar when the pivot joint is locked in its home position.

13. A movable pivot joint as claimed in any one of claims 10 to 12, wherein the end of the locking lever opposite the pivot connection of the locking lever to the slide component is formed with a thumb or finger grip portion.

14. A movable pivot joint as claimed in any one of claims 9 to 13 wherein the frame mounting member of the window stay has a channel shaped profile in transverse cross-section and edge parts of the frame mounting member on either longitudinal side of the frame mounting member engage in grooves on either side of the slide component to capture the slide component for sliding movement on the frame mounting member.

15. A movable pivot joint as claimed in any one of claims 2 to 6, wherein the pivot connection between the arm of the window stay and the locking lever and the slide component comprises an annular shoulder or upstand projecting from the slide and co-axially through a hole in the end of the locking lever and a hole in the end of the arm so that the locking lever and the arm are located about the annular upstand, and a headed fixing means fixed in the interior of the annular upstand to hold the locking lever and arm in position and apply friction to the joint.

16. A window stay as claimed in any one of the preceding claims also comprising an arm pivotally connected at one end to the sash mounting member of the window stay, a protrusion on the other end of said arm, and a slot and/or one or more holes in the long arm of the window stay into which the protrusion may be engaged with the length of the arm being such that when the protrusion is entered into the slot or hole the stay may be opened only to a limited extent.

17. A window stay substantially as herein described with reference to any one or more of the accompanying drawings.